Lithium salt grafted nanocrystalline cellulose for solid polymer electrolyte

Abstract

A solid polymer electrolyte for a battery is disclosed. The solid polymer electrolyte includes a polymer capable of solvating a lithium salt, a lithium salt, and nanocellulose in the form of nanofibers or nanocrystals onto which are grafted anions of lithium salt, the nanofibers or nanocrystals cellulose providing increased mechanical strength to the solid polymer electrolyte to resist growth of dendrites on the surface of the metallic lithium anode.

What is claimed is: 
     
         1 . A nanocrystalline cellulose grafted with anions of lithium salt. 
     
     
         2 . The nanocrystalline cellulose of  claim 1 , wherein the grafted anions are those of the lithium salts selected from the group consisting of SO 2 NLiSO 2 R, SO 2 CLiRSO 2 R and SO 2 BLiSO 2 R. 
     
     
         3 . The nanocrystalline cellulose of  claim 2  wherein R is either a linear or cyclic alkyl or aryl or alkyl fluoride or ether or ester or amide or thioether or amine or quaternary ammonium or urethane or thiourethane or silane or a mixture of these groups. 
     
     
         4 . The nanocrystalline cellulose of  claim 2  wherein R is either an hydrogen or a fluorine or a chlorine or a iodine or a bromine atom. 
     
     
         5 . The nanocrystalline cellulose of  claim 1  wherein the grafted anions of the lithium salt is LiTFSI. 
     
     
         6 . A solid polymer electrolyte for a battery, the solid polymer electrolyte including a polymer capable of solvating a lithium salt, a lithium salt, and nanocellulose in the form of nanofibers or nanocrystals onto which are grafted anions of lithium salt. 
     
     
         7 . A solid polymer electrolyte as defined in  claim 6  wherein the lithium salt LiSalt is selected from the group consisting of LiCF 3 SO 3 , LiB(C 2 O 4 ) 2 , LiN(CF 3 SO 2 ) 2 , LiC(CF 3 SO 2 ) 3 , LiC(CH 3 )(CF 3 SO 2 ) 2 , LiCH(CF 3 SO 2 ) 2 , LiCH 2 (CF 3 SO 2 ), LiC 2 F 5 SO 3 , LiN(C 2 F 5 SO 2 ) 2 , LiN(CF 3 SO 2 ), LiB(CF 3 SO 2 ) 2 , LiPF 6 , LiSbF 6 , LiClO 4 , LiSCN, LiAsF 6 , LiBF 4 , and LiClO 4 . 
     
     
         8 . A solid polymer electrolyte as defined in  claim 6  wherein the grafted anions on the nanocrystalline cellulose are those of lithium salt selected from the group consisting of SO 2 NLiSO 2 R, SO 2 CLiRSO 2 R and SO 2 BLiSO 2 R. 
     
     
         9 . A solid polymer electrolyte as defined in  claim 6  wherein the lithium salt is LiTFSI. 
     
     
         10 . A solid polymer electrolyte as defined in  claim 8  wherein R is either a linear or cyclic alkyl or aryl or alkyl fluoride, an ether, ester, amide, thioether, amine, quaternary ammonium, urethane, thiourethane, silane or a mixture of these groups, R may also be an hydrogen or a fluorine or a chlorine or a iodine or a bromine atom. 
     
     
         11 . A solid polymer electrolyte as defined in  claim 6 , consisting of a nano-composite comprising poly (ethylene oxide) chains blended with a nanocrystalline cellulose onto which are grafted anions of lithium salt. 
     
     
         12 . A battery having a plurality of electrochemical cells, each electrochemical cell including a metallic lithium anode, a cathode, and a solid polymer electrolyte positioned between the anode and the cathode, the solid polymer electrolyte including a polymer capable of solvating lithium salt, a lithium salt, and a nanocrystalline cellulose onto which are grafted anions of lithium salt.